William F. Friedman is a name that might not be familiar to you unless you are a bit of a cryptography nut. Of course, I am a bit of one: I have a couple of long technical notes that were authored by Friedman on the cracking of some complex WWI era ciphers. But I must admit that I've barely scratched the surface of a very fascinating man and his career. The following article talks about Friedman's work on steganography (the hiding of information in plain sight) and its relationship with Bacon's cipher. Pretty neat stuff, and includes some material I had never seen before.